Method of manufacturing and treating asphalt biscuits



April 22, 1930. A, GLIDDEN ET AL METHOD OF MANUFACTURING AND TREATING ASPHALT BISCUITS Filed June 13, 1928 2 Sheets-Sheet 1 April 22, 1930. L D ET AL 1,756,011

METHOD OF MANUFACTURING AND TREATING ASPHALT BISCUITS Filed June 13, 1928 2 Sheets-Sheet 2 g Ii 4/ g: I l l g 59 l I I J {i I: II 7 2%16 8 izi fi l m /9 J3 i4 "fl 55 J0" I 5 l 159 l fivucwworij/ Patented Apr. 22, 1930 UNITED STATES PATENT OFFICE ALFRED A. GLIDDEN, OF WATERTOWN, AND ALAN R. LUKENS, OF BELMONT, MASSA- CHUSETTS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO HOOD RUBBER COMPANY, INC., 0F WATERTOWN, MASSACHUSETTS, A CORPORATION OF DELAWARE METHOD ,OF MAN UEACTURING AND TREATING ASPHALT BISCUITS Application filed June 13,

This invention relates to an improved method of manufacturing and treating asphalt biscuits and molding them to form articles of manufacture, such as battery boxes.

The object of the invention is to provide a method whereby storage battery containers or battery boxes may be manufactured from asphalt compounds and obtain in the finished product uniformity in the physical characteristics of the bituminous concretes which form the construction of these storage battery cases. 7

Great difliculty has been encountered in the manufacture of such articles as one part of the structure would be tough, strong, nonfragile and show high tensile strength and another part would show fragility, low tensile strength and spots of inherent weakness. Due to these disadvantages, storage battery containers of bituminous composition have often proved unsatisfactory as compared with the more expensive storage battery cases which are made from hard rubber.

In the manufacture of storage battery containers under this method predetermined proportions of melted, high melting point and low penetration test bitumens usually asphalts such as gilsonite softened somewhat by a softer asphaltic flux, with acid-resistant, small grained and finely dispersed mineral filler and a cotton fiber or the like, are kneaded or mixed together in a steam-jacketed mixer known as a masticator.

It is necessary that the asphalt cement which binds the mineral filler and cotton fiber or the like together bestiff and not subject to distortion under the high temperature to which a storage battery is often subjected, for example, when the battery is overcharged or placed near the exhaust pipes of an automobile engine.

Bituminous cements with melting point above 250 F. have been found to be the softest that can be used. A bitumen, or more specifically, asphalt of such a character will hardly be soft enough to properly cement, coat and acid-proof the filler and fiber below 300 F; The usual mixing temperature is aboutthat which can be secured by the use of 60 to 100 pounds of steam ordinarily used 1928. Serial No. 285,133.

in a jacketed mixing machine. Too high a temperature will burn the most commonly used fiber, which is cotton. Too low a temperature will fail to liquefy the bitumen sufficiently to properly acid-proof the fiber. It therefore follows that when the ingredients forming the asphalt compound have been completely mixed to a homogeneous mass, this mass must be removed without undue delay.

Heretofore it has been the custom to remove a certain amount of the mixed asphalt compound and while it is warm, place it in the mold and mold the same to form the battery box, the handling of the asphalt mass which is to be molded'into a box being of sufiicient amount to weigh about nine pounds, and the lid of the mixer necessarily being opened and the contents and the stock being weighed exposed to the normal room temperature which is usually 250 F. cooler than the stock, results in the stock removed to the mold presses not being of uniform temperature.

When this stock is chilled so that it loses as little as 100 F., portions of it drop below the solidifying point of the asphalt and it becomes tough, knotty and incompressible. These portions, when pressed along with other warmer parts of the biscuit often yield battery boxes with partitions which have flaws in them. It has been found by careful study of asphalts and similar bituminous compounds that these materials undergo peculiar internal changes when suddenly or ununiformly cooled or aged and it is to overcome these difiiculties and undesirable results obtained that this method has been de vised, namely the stock after being mixed in a heated condition to form the asphalt compounds is passed through sheeting rolls or is placed in a low pressure pressing device which will form it into a slab-like sheet or blank, known as a biscuit. This biscuit is allowed to cool naturally to a room or normal temperature and as such is tough, strong and breakable only with great difliculty. Normal disturbances such as sunlight, variations in normal temperatures or dampness fail to harm it, and it develops valuable in- 10 creases in toughness and strength as it ages.

This toughening is due, it is believed, to lnternal molecular rearrangement and crystallization of the bitumen. It would not be hours are placed in a heating oven hereinafter v descrlbed, and are uniformly. and not too quickly brought to a. uniform and proper molding temperature. By this method the product obtained will be free from the undesirable un-uniformity of structure which would be caused by certain parts of the biscult being chilled or of different temperatures, and thus varying in their characteristics.

The invention consists in the improved method hereinafter set forth and particularly pointed out in the claims.

As hereinbefore stated, a certain amount of high melting point and low penetration test bitumens, such as asphalts softened somewhat by an asphaltic flux, are mixed while heated in a masticator or other suitable mixlng machine with acid resistant, small grained and finely disbursed mineral filler and a cotton fiber or the like. A predetermined quantity of the asphalt compound thus obtained s weighted and passed through sheeting rolls set apart at a predetermined distance or may be placed in a lowp'ressure press which will form it into a slab-like sheet or blank. This blank is then allowed to become cold and age. It is then placed in a heater, one embodiment of which is. illustrated in Figs. 1 and 2 of the drawings.

\ Referring to the said Figs. 1 and 2, Fig. 1 is a front elevation partly in section of an asphalt biscuit heater adapted to heat the biscuits to the proper temperature anduniformly throughout.

Fig. 2 is a sectional elevation, taken on line 22 of Fig. 1, viewed in the direction of the arrows on said section line. The heater consists of a casing 5 having an outer wall 6 and an inner wall 7 with suitable insulating material 8 interposedtherebetween. A pair of conveyors 9 and 10 are provided which consist' of continuous chains 11 and 12 with brackets 13 and 14 incorporated therein. The said brackets have shelves 15 and 16 attached thereto and upon these shelves rest trays 17 upon which'are placed biscuits 18. .The conveyors 9 and. 10 are moved in the direction of the arrows a and b by sprocket gears 19 and 20 and idler sprocket wheels 21 and 22.

The sprockets 19 and 20 are fastened to shafts 23 and 24, and these shafts are rotatably mounted upon brackets 25 supported upon a partition 26 fast to the frame of the machine. The sprockets 21 and 22 are supported on brackets 27 which, in turn, are mounted upon a partition 28. It will be understood that the sprockets 19, 20, 21 and 22 are arranged in pairs and this also is true of the chains .of the conveyors 9 and 10.

The shelves 15 are arranged in staggered relation to each other so that when the trays are placed upon them, the chamber 29 willbe divided by said shelves and trays thereon, the latter forming bafiles so that a current of heated air passing downwardly through the heater will be diverted from the front to the back alternately of said heater.

- Heaters, preferably electric heaters 30, are provided in the lower part of the chamber 29 and air is forced through said chamber from the top downwardly through the heatersand out from the chamber 29 through a pipe 31 by a blower 32 driven by an electric motor 33 and connected by a vertical pipe 34 to a pipe 35 and through a pipe 36. which extends through the top of the heater into the upper part of the chamber 29 again, and as this heated air passes downwardly, it will be dito back and vice versa throughout the entire extent of the portion of the chamber which is filled with trays.

vverted by the trays on the shelves from front In the upper part of the heater there is provided a door 37 which is pivoted at 38 to the casing and is swung inwardly when it is desired to place a tray. with a biscuit thereon upon the shelves. A shelf 39- is provided upon which the tray rests as it is being pushed into the chamber 29 and onto the shelves 15- and 16 as illustrated in Fig. 2.

The conveyors 9 and .10 have motion impartedto them by-rotatingahandle 40 which is fastened to a shaft 41 mounted upon a bracket 42 fast to the casing 5. The shaft 41 has a sprocket 43 fast thereto which drives a sprocket chain 44 which, in turn, drives a sprocket gear 45 fast to the shaft 23, and whereby the sprocket gears 19 tare driven. The shaft 41 has a gear 46 fast thereto which meshes into agear 47 which is fast to a shaft 48 mounted upon the bracket 42 and casin 5, and to the shaft 48 is' fastened a sprodliet gear" 49 which drives achain. 50 which, in' turn, drives a' sprocket ear 51 fast to the shaft 24 to which the pa r of sprocket gears 20 are fastened.

' It will be seen that by rotating the handle 40, the gears 45 and 51 will be rotated in the direction of the arrows thereon, see Fig. 1. This will cause the conveyors 9 and 10 to be moved in the direction of the arrows aand b trays and the biscuits thereon will be moved downwardly through the chamber and slide off onto a drawer 52, which is slidably mounted on a shelf 53 and is pulled outwardly from the casing by ports 55.

It will be seen that the biscuits after having cooled, are thus heated by the heater heremeans of a handle 54 onto supinbefore described and will be heated uniformly and to a certain temperature approximately 300 throughout as they are moved through the chamber very slowly so as to become thoroughly and uniformly heated during their passage therethrough. The biscuit having thus been heated uniformly throughout, is then taken to a mold press and inserted therein and formed to the shape of a battery box, or any other article which may be desired.

The important part of the method hereinbefore described is to age the biscuits after they have been first mixed, heated and formed in a press in order to secure the required toughness and strength, and then uniformly resoftening the biscuits by heat so as to produce a biscuit which is uniform in its characteristics throughout and of the same temperature throughout before molding the same in a suitable mold to form the desired article.

The heater hereinbefore described is to be made the subject-matter of an application for Letters Patent.

. We claim:

1. A method of manufacturing and treating asphalt biscuits which consists in heating and mixing an asphalt compound and pressing the mixture into sheet form to make a biscuit, then allowing the said biscuit to become cold and age, and then reheating it slowly and uniformly until it becomes plastic.

2. A method of manufacturing and treating asphalt biscuits which consists in heating and mixing an-asphalt compound and pressing the mixture into sheet form to make a hiscuit, then allowing the said biscuit to become cold and age, then placing the biscuit in a. chamber and heating it slowly and uniformly until it becomes plastic.

3. A method of manufacturing and treating asphalt biscuits which consists in heating and mixing bitumens with a mineral filler-and a cotton fiber or the like, rolling the mixture into sheet form to make a biscuit, then allowing the said biscuit to become cold and age, then placing the biscuit in a chamber and moving it slowly therethrough while subjecting it to heat until it becomes uniformly heated and plastic.

4. A method of manufacturing and treating asphalt biscuits which consists in heatmg and mixing bitumens with a mineral filler and a cotton fiber or the like, rolling the mixture into sheet form to make a biscuit, then allowing the said biscuit to become cold and age, then placing the biscuit in a chamber and subjecting it to a current of heated gaseous substance until it becomes slowly and uniformly heated and plastic.

5. A method of manufacturing and treating asphalt biscuits which consists in heating and mixing bitumens with a mineral filler and a cotton fiber or the like, rolling the mixture into sheet form to make a biscuit, then allowing the said biscuit to become cold and age, then placing the biscuit in a chamber and moving it therethrough while subjecting it to a current of heated gaseous substance until it becomes slowly and uniformly heated and plastic.

6. A method of manufacturing and treating asphalt biscuits which consists in heating and mixing bitumens with a mineral filler and a cotton fiber or the like, rolling the mixture into sheet form to make a biscuit, then allowing the said biscuit to become cold and age, then placing the biscuit in a chamber and moving it slowly therethrough while subjecting it to a current of gaseous substance heated to approximately 300 F. whereby it becomes slowly and uniformly heated.

7. A method of manufacturing and treating asphalt biscuits which consists in heating and mixing an asphalt compound and pressing the mixture into sheet form to make a biscuit, then allowing the said biscuit to become cold and age, and then reheating it until itbecomes plastic, then molding it while in a our hands.

. ALFRED A. GLIDDEN.

ALAN R. LUKENS. 

